Datasheet

21
LTC1197/LTC1197L
LTC1199/LTC1199L
MICROPROCESSOR INTERFACES
The LTC1197/LTC1197L/LTC1199/LTC1199L can inter-
face directly (without external hardware to most popular
microprocessor (MPU) synchronous serial formats (see
Table 1). If an MPU without a dedicated serial port is used,
then three or four of the MPU’s parallel port lines can be
programmed to form the serial link. Included here is one
serial interface example and one example showing a
parallel port programmed to form the serial interface.
Motorola SPI (MC68HC05C4, MC68HC11)
The MC68HC05C4 has been chosen as an example of an
MPU with a dedicated serial port. This MPU transfers data
MSB-first and in 8-bit increments. With two 8-bit trans-
fers, the A/D result is read into the MPU. The first 8-bit
transfer sends the D
IN
word to the LTC1199 and clocks the
two ADC MSBs (B9 and B8) into the MPU. The second 8-
bit transfer clocks the next 8 bits, B7 through B0, of the
ADC into the MPU.
ANDing the first MPU received byte with 03Hex clears the
six MSBs. Notice how the position of the start bit in the D
IN
word is used to position the A/D result so that it is right-
justified in two memory locations.
Table 1. Microprocessor with Hardware Serial Interfaces
Compatible with the LTC1197/LTC1197L/LTC1199/LTC1199L
PART NUMBER TYPE OF INTERFACE
Motorola
MC6805S2,S3 SPI
MC68HC11 SPI
MC68HC05 SPI
RCA
CDP68HC05 SPI
Hitachi
HD6301 SCI Synchronous
HD6303 SCI Synchronous
HD6305 SCI Synchronous
HD63701 SCI Synchronous
HD63705 SCI Synchronous
HD64180 CSI/O
National Semiconductor
COP400 Family MICROWIRE
TM
COP800 Family MICROWIRE/PLUS
TM
NSC8050U MICROWIRE/PLUS
HPC16000 Family MICROWIRE/PLUS
Texas Instruments
TMS7000 Family Serial Port
TMS320 Family Serial Port
Microchip Technology
PIC16C60 Family SPI, SCI Synchronous
PIC16C70 Family SPI, SCI Synchronous
MICROWIRE and MICROWIRE/PLUS are trademarks of
National Semiconductor Corp.
TYPICAL APPLICATIO S
U